JP2506692B2 - Photo flash device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic strobe device in which a transistor is connected as a light emission control element in series with a flash discharge tube, and particularly to a photographic strobe device characterized by an operation control system of the transistor. It relates to the device.

2. Description of the Related Art Conventionally, a photographic strobe device in which a flash discharge tube and a transistor as an emission control element are connected in series is known, for example, from Japanese Utility Model Publication No. 43-21344.

However, since the above-mentioned conventional device is configured to constantly supply the base current of the transistor connected in series with the flash discharge tube, there is a problem that power consumption is increased except for the light emitting operation which is the main operation. are doing.

That is, it becomes necessary to continue the non-conducting operation of the transistor from the supply of the base current itself or the configuration until the flash discharge tube is completely extinguished, and as a result, the non-conducting operation varies in the flash discharge tube. Considering the characteristics of
This has to be done for a relatively long period of time, resulting in a large amount of power consumption.

Therefore, the applicant of the present application has previously proposed, in Japanese Patent Application No. 60-215439, a photographic strobe device capable of solving the above-mentioned problems of the conventional device.

The photographic strobe device in this proposal has a basic configuration as shown in FIG. 6, and its operation will be briefly described as follows.

When the power switch 2 is closed, the well-known DC-DC converter circuit 3 boosts the terminal voltage of the low-voltage battery 1 which is a low-voltage power source, and the well-known trigger circuit 7 for exciting the main capacitor 4 and the flash discharge tube 5. The trigger capacitor Gr is charged. At the same time, the output of the control means 8 is set to a steady state which keeps the transistor 10 off. The steady state may be set when the main capacitor 4 and the like are fully charged.

When the synchro switch S is closed while the main capacitor 4 and the like are charged, the flash discharge tube 5 is excited and the synchronous switch S ₁ is closed, and the control means 8 shifts from the steady state to the output state in which the transistor 10 is turned on. At this time, the transistor Tr which is the switch element 11 is kept off.

When the transistor 8 is turned on, a parallel body composed of the transistor 1, the capacitor C and the current limiting resistor R from the battery 1
The base current of the transistor 6 is supplied via 12 and, as a result, the flash discharge tube 5 emits light. At this time, the supply of the base current sharply rises by the parallel body 12 and is controlled to a value determined by the resistor R after the charging of the capacitor C is completed.

On the other hand, when the amount of light emitted from the flash discharge tube 5 reaches a desired amount, the light emission stop signal generation means 9 operates and supplies the light emission stop signal to the control means 8.

Upon receiving the light emission stop signal, the control means 8 returns to the steady state again, and the transistor 10 is turned off. still,
In this case, the transistor Tr, which is the switch element 11, is turned on by the charge stored in the capacitor C of the parallel body 12.

Accordingly, the base current of the transistor 6 is cut off when the transistor 10 is turned off, and at the same time, it is reverse-biased by the voltage drop caused by the discharge of the capacitor C through the resistor R, so that the transistor 6 is instantly and certainly turned off. At this point, the flash discharge tube 5 also stops emitting light.

The following operation is the operation of the photographic strobe device previously proposed, and the transistor connected in series with the flash discharge tube is
It conducts based on the operation of the trigger circuit, and becomes non-conducting due to the cutoff of the base current based on the output of the light emission stop signal and the reverse bias, that is, it operates only when necessary. Therefore, the light emitting operation, which is the main operation compared to the conventional device, is performed. Power consumption in operations other than can be reduced.

Problems to be Solved by the Invention As described above, the above proposed device has an effect of improving the problems of the conventional device. On the other hand, considering the signal output from the control means 8, first, the steady state is reached. High level signal to keep transistor 10 off, low level signal to keep transistor 10 on in synchronization with the operation of the trigger circuit, high level to keep transistor 10 off again by receiving the light emission stop signal Output signal,
Needless to say, such a signal becomes a pulse signal output.

Therefore, in consideration of practical use, a pulse generation circuit for forming a pulse signal at the above-described timing is specially required as the control means, and the cost of the control means 8 increases. It will be.

The present invention has been made in view of the above points, and provides a photographic strobe device in which the control means is configured by utilizing the circuit configuration of a conventional strobe device to reduce the cost. With the goal.

A photographic strobe device according to the present invention comprises a first series body composed of a flash discharge tube and a first transistor connected to both ends of a main capacitor charged by a high voltage DC power supply, and a first series body. A second series body composed of a second transistor, a current control element, and a parallel body of a capacitor connected to both ends of the low-voltage power supply via the base and emitter of the first transistor; and the first transistor. A switch element connected between the base and the emitter through the parallel body, and a trigger circuit that operates by receiving a trigger signal that is a pulse signal formed by closing the synchro switch of the camera to excite the flash discharge tube. A light emission stop signal generation circuit for detecting a time point when a desired amount of light is emitted from the flash discharge tube and outputting a light emission stop signal for the flash discharge tube; The first control switch means for receiving the trigger signal to operate to turn on the second transistor and control the switch element to the off state, and to detect a light emission of the flash discharge tube to output a predetermined voltage. A voltage generation circuit for maintaining the first control switch means in an operating state during light emission of the flash discharge tube by supplying a predetermined voltage output to the first control switch means, and light emission from the light emission stop signal generation circuit. And a second control switch means for operating in response to a stop signal to stop the operation of the first control switch means to turn off the second transistor and turn on the switch element.

Since the photographic strobe device according to the present invention has the above-described structure, the first strobe device connected in series with the flash discharge tube is provided.
The low voltage power source is supplied through the second transistor and the parallel body by turning on the second transistor and turning off the switch element by the operation of the first control switch means based on the trigger signal. It is turned on, and its on state is maintained during the light emitting operation of the flash discharge tube by maintaining the operating state of the first control switch means by the voltage generating circuit. Further, the first transistor operates in response to the light emission stop signal to stop the operation of the first control switch means and the second transistor.
By the operation of the second control switch means for turning off the transistor and turning on the switch element, the reverse bias due to the charge of the capacitor of the parallel body is simultaneously performed via the switch element at the same time as the supply of the low voltage power supply is stopped. Therefore, the off operation is performed reliably and in a short time.

Embodiment 1 FIG. 1 is an electric circuit diagram showing an embodiment of a photographic strobe device according to the present invention, in which the same reference numerals as those in FIG. 6 indicate the same components.

As is apparent from FIG. 1, also in this embodiment, as in the proposed device shown in FIG. 6 above, the transistor Tr is used as the switch element 11.

In the figure, a trigger circuit 13 is provided with a structure for exciting the flash discharge tube 5 by supplying a trigger signal, which is a pulse signal disclosed in, for example, JP-A-51-96321, from an input terminal 14.

The voltage generation circuit 15 turns on the transistor 17 by the discharge of the charge of the capacitor 16 that has been charged in advance before light emission due to the light emission of the flash discharge tube 5, and is precharged to a predetermined value regulated by the Zener diode 18. The charging voltage of the capacitor 19 is output to the output terminal 20 and is supplied to, for example, the light emission stop signal generating circuit 9.

The dividing means 21 is means for dividing the predetermined voltage output to the output terminal 20 of the voltage generating circuit 15.

The transistors 22 and 23 turn on the transistor 10 by turning on respectively, and keep the switch element 11 off, and turn off the transistor 10 by turning off the switch element 11, respectively.
The first control switch means 24 is configured to control 11 to be in an electrically floating state, that is, an on-state. The bases of the transistors 22 and 23 are connected to the input terminal 14 and the dividing means 21.

Transistor 26 turns on when turned on.
Second control switch means 2 for short-circuiting the bases and emitters of the transistors 22,23 to turn off both the transistors 22,23
Forming 5

As shown by the broken line in the figure, a diode may be connected between the connection point between the input terminal 14 and the bases of the transistors 22 and 23 if necessary, and the dividing means 21 is a voltage generating circuit.
It goes without saying that it can be omitted depending on the voltage value output by 15.

Now, in FIG. 1, when the power switch 2 is closed, the DC-DC converter circuit 3 boosts the terminal voltage of the low-voltage battery 1 which is a low-voltage power source, and the main capacitor 4 and the capacitor of the voltage generation circuit 15 are connected. Charge 16, 19, etc.

At this time, the output terminal 20 of the voltage generation circuit 15 is at a low level, and the trigger signal is not input to the input terminal 14, so that the transistor 22 is turned off, so that the transistor 10 is kept off and the transistor 7 is turned on. Never,
Of course, the transistor 23 and the transistor Tr that is the switch element 11 are also off.

When the trigger signal is supplied with the main capacitor 4 etc. charged, the trigger circuit 13 operates and the transistors 22 and 23 are momentarily turned on, the transistor 10 is turned on, and the transistor Tr is turned off. Therefore, similarly to the device described in FIG. 6, the base current of the transistor 6 is supplied through the parallel body 12 to turn on the transistor 6, and as a result, the flash discharge tube 5 emits light.

When the flash discharge tube 5 emits light, the voltage generating circuit 15 operates as described above to generate a predetermined voltage at its output terminal 20 and supplies it to the light emission stop signal generating circuit 9 and the dividing means 21.

The predetermined voltage supplied to the dividing means 21 is appropriately divided and supplied between the base and emitter of each of the transistors 22 and 23, and the ON state of both the transistors turned on by the trigger signal is maintained even after the trigger signal disappears. To do.

Therefore, the transistor 10 is kept on, and thus the transistor 6 is also kept on, so that the light emission operation of the flash discharge tube 5 is continued.

When the light emission stop signal generation circuit 9 operates during light emission and a light emission stop signal is output from its output terminal, the transistor 26 is turned on and the bases of the transistors 22 and 23 are turned on.
Short the emitters and turn off both transistors 22 and 23.

Therefore, transistor 10 is turned off and parallel body 12
The transistor Tr is turned on by the charged electric charge of the capacitor C, and the transistor 6 is reversely biased while the base current is cut off as in the device shown in FIG. The light emission of the tube 5 will stop.

The above operation is the operation of the photographic strobe device according to the present invention shown in FIG. 1. As is apparent from the above description, once the transistor 10 is turned on in response to the trigger signal, the transistor 10 is turned on thereafter. The ON state is maintained by the output of the voltage generating means 15, and the operation equivalent to that of the device shown in FIG. 6 is performed without using a special pulse generating circuit. Needless to say, the same operation is performed when the diode shown by the broken line is connected.

FIG. 2 is a partial electric circuit diagram showing another embodiment of the photographic strobe device according to the present invention, in which the same reference numerals as in FIG. 1 designate the same members.

In this embodiment, between the output terminal 20 of the voltage generating circuit 15 and the light emission stop signal generating circuit 9, the power source capacitor 27 charged by the predetermined voltage generated at the output terminal 20 and the power source capacitor 27 are provided. The diode 28 is provided to control so that the charging voltage is supplied only to the light emission stop signal generating circuit 9, that is, not supplied to the dividing means 21.

With the above configuration, the light emission stop signal generation circuit 9 can output the light emission stop signal for the predetermined period even after the output of the predetermined voltage by the voltage generation circuit 15 is stopped.
That is, the operation of the light emission stop signal generating circuit 9 can be controlled so that it is always after the voltage output operation of the dividing means 21 is completed.

3 (a) and 3 (b) are partial electric circuit diagrams showing still another embodiment of the photographic strobe device according to the present invention, in which the same reference numerals as in FIG. 1 denote the same members. There is.

The embodiment shown in FIGS. 3 (a) and 3 (b) is an example in which a thyristor SCR ₁ or SCR ₂ is used as the switch element 11 which used the transistor Tr in FIG.

The example shown in FIG. 3 (a) is the SCR ₁ which is the switch element 11.
Connect its anode to the connection point between the transistor 10 and the parallel body 12, and connect its cathode to the ground line.
This is an example in which resistors R ₁ and R ₂ are connected between the gates and between the gate and the cathode, respectively, and a transistor 23 is connected between the gate and the cathode. The operation is exactly the same as that of the embodiment shown in FIG. .

That is, SC which is the switch element 11 shown in FIG.
R ₁ is maintained in the OFF state by short-circuiting the gate and the cathode by turning on the transistor 23 by the supply of the trigger signal and the predetermined voltage from the dividing means 21, and the transistor 26 by the output of the light emission stop signal from the light emission stop signal generating circuit 9 Turning on turns off the transistor 23
The gate voltage is supplied via R ₁ and R ₂ to turn on.

In the embodiment shown in FIG. 3 (b), as is clear from the drawing, the SCR ₂ which is the switching element 11 has its anode at the connection point of the transistor 10 and the parallel body 12, its cathode at the ground line, and The gates are respectively connected to the connection points of the capacitor C _G and the resistor R _G forming the gate circuit 29.

Further, the gate circuit 29 is connected to the base of the transistor 10 via the diode D _{G and} to the emitter of the transistor 10, ie, the power supply side, via the resistor R ₃ .

In FIG. 3B, the capacitor C _G of the gate circuit 29
Is charged to the polarity shown by turning on the power switch 2,
For the light emission operation, that is, when the transistor 22 is turned on by the supply of the trigger signal, the transistor 22 and the diode D _G are discharged, and when the transistor 26 is turned on by the light emission stop signal, the transistor 22 is turned off to be charged to the polarity shown again. During such recharging, the thyristor SCR ₂ is turned on by the charging voltage of the capacitor C of the parallel body 12. Therefore, in such an embodiment,
The gate circuit 29, the resistor R ₃ , the diode D _G and the transistor 22 function as the second control switch means 24.

FIG. 4 is a partial electric circuit diagram showing still another embodiment of the photographic strobe device according to the present invention, in which the same reference numerals as those in FIG. 1 denote the same members.

In this embodiment, instead of the low voltage battery 1 which is also supplied to the DC-DC converter circuit 3 used as a low voltage power source which serves as a base current supply source for turning on the transistor 6 in FIG. 1, a DC-DC converter is used. Add the auxiliary winding l _S are each winding electromagnetically coupled to the oscillation transformer T ₃ in the circuit 3,
Via the diode D to use a capacitor C _E, which is charged by the voltage induced in the auxiliary winding l _S, i.e. an example of using the electric charge of the capacitor C _E as low-voltage power source which is a supply source of the base current Is.

In this case, the supply voltage to the parallel body 12 or the like can be made higher than that in the case of only the low voltage battery 1. On the other hand, when the supply voltage is made higher than the above case, the charging voltage of the capacitor C of the parallel body 12 is When the transistor 6 is reverse biased, this transistor 6 may become
Therefore, it is preferable to connect a Zener diode ZD having an appropriate breakover voltage in parallel to the parallel body 12 as shown by the broken line in FIG.

FIG. 5 is a partial electric circuit diagram showing still another embodiment of the photographic strobe device according to the present invention. In FIG.
The same reference numerals as those in FIG. 4 indicate the same members.

In this embodiment, the voltage of the low-voltage power supply is detected on the low-voltage power supply side that is the supply source of the base current for turning on the transistor 6,
A voltage detection circuit 30 is provided for forcibly stopping the supply of the base current to prevent light emission when the value is equal to or less than a predetermined value.

This voltage detection circuit 30 divides the voltage of the low-voltage power source, which is the source of the base current of the transistor 6, into division resistors R ₄ , R ₄ .
_5, the split resistor R _4, a divided voltage of R ₅ is compared with a reference voltage of the reference power source E _S, outputs a low level signal when the divided voltage is less than the reference voltage, the input terminal 14 a low-level trigger signal And a comparator 31 forcibly turning off the transistors 22 and 23.

In addition, a dividing resistor that divides the charging voltage of the main capacitor 4
R _6, R _7, an output terminal 31a and connected to the control input terminal 33a of the comparator 31, an operational state when a high level signal is input to the terminal 33a, the dividing resistors R _6, R ₇
There is also provided a voltage display circuit 32 including a control unit 33 for turning on the display LED 34 when the divided voltage by is equal to or more than a predetermined value.

Further, the reference numeral 35 shown by a broken line indicates a high-voltage external power source formed so as to be usable as a power source.

The control system of the transistor 6 in this embodiment is
It goes without saying that it is based on FIG. 3 (a) and FIG.

With the above configuration, the following disadvantages that may occur when the flash discharge tube 5 is repeatedly made to emit light or when the external power source 35 is used can be solved.

That is, in the case as described above, the charging voltage of the main capacitor 4 is sufficient, but the terminal voltage of the low-voltage power supply side that supplies the base current of the transistor 6 is not sufficient, and the desired base current cannot be supplied. There is a risk of causing inconvenience such as destruction.

However, in the embodiment shown in FIG. 5, the voltage detection circuit 30 operates in the above case and the comparator
31 outputs a low level signal to its output terminal 31a to block the trigger signal and forcefully turn off the transistors 22 and 23.

Therefore, if the flash discharge tube 5 is emitting light, the transistor 26
The transistor 10 is turned off and the SCR ₁ is turned on as in the case where the transistor is turned on, and the base current of the transistor 6 is cut off and the transistor 6 is reverse-biased.

Further, when the flash discharge tube 5 is not emitting light, the trigger signal is blocked, so that the next light emitting operation is controlled.

That is, in either case, the base current of the transistor 6 is not supplied and light emission is blocked. As a result, in the case of repeated light emission, the transistor 6 is destroyed by the light emitting operation due to insufficient base current supply. There is no such thing.

EFFECTS OF THE INVENTION As described above, the photographic strobe device according to the present invention uses the voltage generating circuit that the strobe device normally has to supply the base current of the transistor connected in series to the flash discharge tube. Since the base current is supplied only when necessary, that is, in a pulsed manner, there is an effect that a pulse generating circuit for forming a pulse signal is not particularly required.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of a photographic strobe device according to the present invention, and FIG. 2, FIG. 3, (a), (b), FIG. 4, and FIG.
FIG. 6 is a circuit diagram showing the essential parts of another embodiment of the photographic strobe device according to the present invention. FIG. 6 is an electric circuit diagram showing the basic construction of the photographic strobe device proposed by the applicant of the present application in Japanese Patent Application No. 60-215439. 1 ... Battery, 2 ... Power switch, 4 ... Main capacitor, 5 ... Flash discharge tube, 6 ... Transistor, 11 ... Switch element, 12 ... Parallel body, 13 ... Trigger circuit, 14 ...
… Input terminal, 15 …… Voltage generator, 16,19 …… Capacitor, 17 …… Transistor, 18 …… Zener diode,
20 ... Output terminal, 21 ... Dividing means, 22,23 ... Transistor, 24 ... First control switch means, 25 ... Second control switch means, 26 ... Transistor, 27 ... Power supply capacitor , 28 ... Diode, 29 ... Gate circuit, 30 ...
… Voltage detection circuit, 31 …… Comparator, 32 …… Voltage display circuit, 33 …… Control section, 34 …… Display LED, 35 …… External power supply, SCR ₁ , SCR ₂ … Thyristor, _CG …… Capacitor , R _G
...... resistance, D _G ...... diodes, l _S ...... auxiliary winding, D ......
Diode, C _E ... Capacitor, ZD ... Zener diode.

Claims (11)

(57) [Claims] 1. A first series body composed of a flash discharge tube and a first transistor connected to both ends of a main capacitor charged by a DC high voltage power source, a second transistor, a current control element and a capacitor in parallel. A second series body connected to both ends of a low-voltage power supply via the base and emitter of the first transistor, and connected via the parallel body to the base and emitter of the first transistor. A switch element, a trigger circuit that operates by receiving a trigger signal that is a pulse signal formed by closing the synchro switch of the camera to excite the flash discharge tube, and a desired amount of light is emitted from the flash discharge tube. A light emission stop signal generating circuit for detecting a time point and outputting a light emission stop signal for the flash discharge tube; and a second transistor for operating in response to the trigger signal. And a first control switch means for turning on the switch element and controlling the switch element to an off state, and detecting the light emission of the flash discharge tube to output a predetermined voltage and supplying the predetermined voltage output to the light emission stop signal generation circuit. A voltage generation circuit for maintaining the first control switch means in an operating state during light emission of the flash discharge tube by supplying it to the first control switch means, and a light emission stop signal from the light emission stop signal generation circuit. A photographic strobe device comprising: second control switch means which receives and operates to stop the operation of the first control switch means to turn off the second transistor and turn on the switch element. 2. The switch element according to claim 1, wherein the main electrode is a third transistor whose main electrode is connected to both ends of a series connection body between the parallel body and the base-emitter of the first transistor. Photo flash device. 3. The first control switch means has a second main electrode.
The fourth transistor whose control electrode is connected to the input terminal of the trigger signal and the output terminal of the voltage generating circuit between the base of the transistor of and the ground, and the control electrode of the main electrode between the control electrode of the switch element and the ground. The photographic flash device according to claim 1, comprising a fifth transistor connected to the control electrode of the fourth transistor. 4. The photographic strobe device according to claim 1, wherein the second control switch means is a sixth transistor whose main electrode is connected between the output terminal of the voltage generating circuit and the ground. 5. The light emission stop signal generating circuit charges the power supply capacitor, which is charged with a predetermined voltage output of the voltage generating circuit, through a diode so that the charge is not supplied to the first control switch means. The photographic strobe device according to claim 1, wherein an electric charge is supplied. 6. The switch element has an anode having a parallel body and a second body.
The photographic strobe device according to claim 1, wherein the cathode is a thyristor whose cathode is connected to the ground at the connection point with the transistor. 7. The switch element is a thyristor whose anode is connected to the connection point between the second transistor and the parallel body and whose cathode is connected to the ground, and the first control switch means has a main electrode whose second electrode is the second transistor. Between the base and the ground, the control electrode is composed of a fourth transistor connected to the input terminal of the trigger signal and the output terminal of the voltage generation circuit, and a series body of a capacitor and a resistor connected to both ends of the low-voltage power supply. A gate circuit whose connection point is connected to the gate of the thyristor, and a connection point between the low-voltage power supply and the gate circuit and the base of the second transistor are connected to each other when the fourth transistor is turned on. The photographic strobe device according to claim 1, comprising a diode for discharging the charge charged in the capacitor of the gate circuit. 8. The DC high-voltage power supply is a DC-DC converter circuit, and the low-voltage power supply is charged through a diode by a voltage induced in an auxiliary winding provided in an oscillation transformer of the DC-DC converter circuit. The photographic strobe device according to claim 1, which is a condenser. 9. The photographic strobe device according to claim 1, wherein the parallel body further comprises zener diodes connected in parallel. 10. A first series body composed of a flash discharge tube and a first transistor connected to both ends of a main capacitor charged by a DC high-voltage power supply, a second transistor, a current control element and a capacitor in parallel. A second series body connected to both ends of a low-voltage power supply via the base and emitter of the first transistor and a body connected between the base and emitter of the first transistor via the parallel body. A switch element, a trigger circuit that operates by receiving a trigger signal that is a pulse signal formed by closing the synchro switch of the camera to excite the flash discharge tube, and a desired amount of light is emitted from the flash discharge tube. A light emission stop signal generating circuit for detecting a time point and outputting a light emission stop signal for the flash discharge tube; and a second transition circuit which operates upon receiving the trigger signal. A first control switch means for controlling said switching element to the off state with turn on the motor,
During the light emission of the flash discharge tube, the light emission of the flash discharge tube is detected, a predetermined voltage is output, and the predetermined voltage output is supplied to the light emission stop signal generating circuit and to the first control switch means. A voltage generation circuit for maintaining the first control switch means in an operating state, and a second transistor that operates by receiving a light emission stop signal from the light emission stop signal generation circuit to stop the operation of the first control switch means. Second control switch means for turning off the switch element and turning on the switch element, and detecting the terminal voltage of the low-voltage power supply and blocking the supply of the trigger signal to the trigger circuit when the terminal voltage is equal to or lower than a predetermined value. A photographic strobe device comprising a voltage detection circuit for forcibly controlling the first control switch means to a non-operating state. 11. The DC high-voltage power supply is a DC-DC converter circuit, and the low-voltage power supply is charged via a diode by a voltage induced in an auxiliary winding provided in an oscillation transformer of the DC-DC converter circuit. The photographic strobe device according to claim 10, which is a condenser.